1. Field of the Invention
The present invention relates to the field of aircraft deicing, and in particular, to aircraft deicing methodologies and apparatus using forced air in combination with deicing fluids.
2. Description of the Prior Art
Deicing has traditionally been performed by spraying large quantities of heated antifreeze, or glycol and water mixtures onto the iced surfaces of the aircraft. While this method is effective in deicing, it is associated with increasing costs of glycol and concern with the environmental impact of glycol runoff and wastage. To counter this concern, the prior art has proposed construction of elaborate and expensive multimillion dollar deicing pads wherein the glycol runoff is captured and recycled. Such deicing pads have the disadvantage of not only being very expensive but requiring a specialized structure or area into which the aircraft is driven for deicing. It is preferable to provide a methodology and apparatus which is capable of deicing the aircraft in virtually any convenient location in its ground cycle.
Patterson, "Airplane Wing Deicer," U.S. Pat. No. 2,422,746 (1947) describes a high pressure air and liquid jet positioned at the forward portion of an airplane wing, so that the jet and the fluid ejected by the jet underlies any film of ice that forms on the wing edges and surfaces. The purpose of the jets of air and liquid are to tear off the accumulations of ice and snow on the forward edges of the wing, and to allow the air stream, while the aircraft is flying, to tear off the remaining ice accumulated on the rear and upper surfaces of the wing. However, such a prior art system is inappropriate for present aircraft practices which require deicing prior to takeoff. Furthermore, incorporation in a large jet aircraft of a deicing pattern such as shown by Patterson unnecessarily adds to the expense, complexity, weight and fuel usage of the aircraft and is unnecessary in modern jet aircraft.
Magnusson et al, "Deicing and Cleaning System for Aircrafts," U.S. Pat. No. 4,378,755 (1983) shows a fixed installation deicing structure, similar in concept to a car wash, through which the aircraft is driven when it is deiced. The structure includes two stages or portals. At the first portal, all snow and ice is washed off by hot water. This hot water deicing is accomplished by abundant spraying of heated water. At a second portal, the aircraft is then showered with concentrated glycol to prevent coatings of snow and ice until the aircraft is airborne. Magnusson is an example of the multimillion dollar fixed deicing station which the prior art has sought to offer as a means of reducing glycol usage.
Garrison, "Airplane Wing Deicing Means," U.S, Pat. No. 2,390,093 (1945) describes an airplane wing in which the leading edge is made from a porous metal which allows a quantity of anti-icing fluid to exude and spread uniformly over the outer surface. The anti-icing fluid is atomized and pressurized in a chamber behind the leading porous metal edge. The pressurized atomized fluid may also be heated prior to being pumped into the cavities behind the porous wing edge. The icing fluid then defuses through the sintered metal edge to loosen the ice formed on the leading edge of the wing surface when in flight. Garrison is, thus similar to Patterson for showing a deicing surface installed within a wing surface designed to principally operate under flight conditions and, therefore, shares the same disadvantages as Patterson discussed above.
Sammons, "Prevention of Ice Formation in Air Intakes on Aircraft and Other Fast Moving Vehicles," U.S. Pat. No. 2,482,720 (1949) and Palmatier, "Fan Deicing or Anti-Icing Means", U.S. Pat. No. 2,406,473 (1946) are both directed to various means used in connection with aircraft engines, in which deicing fluid is distribute on selected surfaces of the engine by using part of the air stream created by the driven propeller. In Sammons, hot air exhaust from the engine is used as a means for deicing. A guard is provided to the air intact of a compressor and hot air supplied through jets which flow past the guard. In Palmatier, an air stream is produced by the rotor blades to aid in the distribution of the deicing liquid along the surface of the stator blades. Some of the deicing fluid is entrained in the air stream produced by the rotor and carried there by engagement with surfaces of the stator blades. However, both Palmatier and Sammons are solely concerned with providing air entrained deicing fluid for very specifically restricted surfaces within an aircraft engine and are operable only when the engine is operating. No means is suggested by either as to how the major airfoil surfaces of a standing aircraft can be appropriately deiced by methodology or apparatus which is not built in to the aircraft, and yet which is easily portable and usable at any site during the ground cycle of a landed aircraft.